The main aim of the present study was to investigate the characteristics of products from hydrothermal treatments of cellulose in an autoclave at various temperatures (200 degrees C-400 degrees C) and residence times (5 min-2 h). The gas products mainly consisted of CO2, CO, CH4, and H-2 at 250 degrees C-400 degrees C for 30 min. Heavy oil mainly contained furans, phenols, carboxylic acids, aldehydes, ketones, and high molecular compounds at all hydrothermal temperatures. Aldehydes, phenols, ketones, acid groups and sugars were determined in the aqueous phase by gas chromatography-mass spectrometry and Fourier transform infrared (FTIR). The solid residues were analyzed by elemental analysis, scanning electron microscopy, transmission electron microscopy, x-ray photoelectron microscopy, FTIR, and thermogravimetric analysis techniques. The results showed that the residues had core shell structure and better physicochemical characterization at lower temperature (250 degrees C) and longer residence time (2 h). (C) 2012 Elsevier Ltd. All rights reserved.